HS34 fails during engine start

[RVG8tor]

Sorry up front but I am typing on a small tablet. I am on day two of a trip from Olympia WA to Ft Worth to get the plane painted. Of course this never occured when I flew the first 45 hours. Twice now on this trip my HS34 fails, no lights, buttons don't function, during engine start. Both time it was a hot start after a fuel stop. I am still getting a hang on the hot start procedure but it sometimes takes a couple tries
At first I though lost power but cycling the CB did nothing.

Of course this happens on the last leg into a night landing. Next mornimg all is good then the start after the fuel stop no HS34. This time I shut down, gave myself another chance at a hot start. Cycled the master off then on and did another start, same deal HS34 goes off and 430W reports no 429 data.

I learned a nice tid bit, this one failure basically removes most of my IFR ability because I loose the course and glide path guidance on the EFIS. I still tried the GPS using the 430 CDI but no vertical lathe guidance.

So anyone have ideas? I did look at the DSAB status along the way and it shows the HS34 but does not show that it is fullfillimg its roll. No issues with this to date and I havedone a lot of approach work to get used to using the various boxes.

[Roy Thoma]

I had a similar problem. Dynon replaced my HS34 under warranty and the problem has not happened again.

I could not tell from a quick look at you KitLog if you have an the ability to turn off power to the HS34 and the D1xx. If you do, try to cycle the power to the Dynon stuff after the engine is running. I think I had to leave my off for about 30 seconds get the HS34 talking to my D100. This was a bit uncomfortable as all my engine gauges were off during this time. I trusted (hoped ??) that the engine would continue to work fine at idle.

Regards,

[RVG8tor]

Originally Posted by Roy Thoma

I had a similar problem. Dynon replaced my HS34 under warranty and the problem has not happened again.

I could not tell from a quick look at you KitLog if you have an the ability to turn off power to the HS34 and the D1xx. If you do, try to cycle the power to the Dynon stuff after the engine is running. I think I had to leave my off for about 30 seconds get the HS34 talking to my D100. This was a bit uncomfortable as all my engine gauges were off during this time. I trusted (hoped ??) that the engine would continue to work fine at idle.

Regards,

This is my plan if the weather clears up. I tried powering things up with the HS34 off and then turn it on after the other items boot up and that works on battery power, I will have to wait and see how it does with the alternator on.

I am thinking something internal sees the power surge as the alternator comes online, there is more a surge when I hot start because the throttle is set higher, I think this is why I do not get this on a first start of the day. Although I have had fuel stops in my local testing flight but it was cooler up in the NW and starting took less effort.

I have not had good luck with warrenty from Dynon, I bought my gear like many builders well before I was flying and testing, I had an issue with a new pressure sender and they would not replace it even though it was never used but hopefully this is a different issue. Modern electronics should be able to handle this stuff from what I understand. I am glad I installed all CBs so I can isolate stuff.

I start with the alternator on because I hear it is better for the alternator but I guess on option would be to start with it off and then turn it on after the engine is stable at idle.

Thanks for the input